DE2607014C2 - Microparticles for marking substances - Google Patents

Description

1. Provision of a set of uniquely J5 coded lots of microparticles;

2. Keeping records of the unique code used in each lot; and

3. Introduction of microparticles from one of the lots into only one production unit of a substance.

The invention relates to microparticles for marking production units of a material for the purpose a subsequent identification of this material.

The marking of individual production units of bulk goods is known. The US PS The invention is based on the object of providing microparticles for marking and subsequent identification of substances that can be readily obtained by visual inspection of a single microparticle have it decoded with a microscope or other magnifying device.

The subject matter of the invention is a large number of microparticles that are used to mark substances for the purpose of subsequent identification of the substances are suitable and characterized in that each microparticle has a regular arrangement of at least three visually distinguishable color segments, the Sequence consists of a code which can be read in an information relating to the labeled substance, and that each microparticle measures in its broadest dimension over the color sequence 1 to 1000 μm.

The improvement of the invention lies in the provision of microparticles, which by a certain regular sequential arrangement of visually distinguishable colored segments are coded.

The microparticle inventory can consist of up to [CI (C-1) "- ¹ ] uniquely coded lots, where C is the number of available colors and η is the number of segments in the color sequence. For example, using a catalog of 12 colors with an eight-part sequence and no color at the same time in successive segments, the number of codes is determined as follows:

Segment no .:

12 3 4
Available colours:

12 11 11 11

11 11 11 11

This system contains 233 846 052 possible codes or half that number, depending on the code in both Directions can be read.

Each color code contains at least three color segments to enable a large number of codes.

The broadest dimension of a microparticle over the color sequence is 1 to 1000 μην. however are upper limits of 250 to 300 μm are preferred so that a large number of microparticles per unit weight is possible. The preferred microparticles lie in the range from 50 to 250 μm in the widest dimension above the color sequence. Below 50 μπι can Codes become more difficult to identify: then a complex device may have to be used.

To facilitate separation from the bulk cargo, in which they are located, the microparticles also preferably have a distinctive shape on. Spherical, cylindrical, polygonal and other geometric shapes are easily recognizable, and such Particles can be easily separated from conventional particulate substances.

The different types of color-coded micro-identifiers and the methods of making them will now be explained with reference to the accompanying drawings, in which FIG. 1 to 4 times Perspective views of various designs of color-coded microparticles and FIGS. 5 and 6 schematically the production of the embodiment according to FIG. 4 show.

F i g. 1 shows a spherically designed microparticle J5 20, which is to be referred to here as "onion globules" and contains a preformed solid core 22. on this core are colored or dyed layers 24 of polymer material applied concentrically in such a way that that two successive layers are not the same Have color. Each layer represents an assortment of the identifying code. In conventional coating processes the mean thickness of each layer is about 25 μm.

After the onion globule is recovered from the marked substrate, it is halved? or in spherical segments cut up and read the color code from the resulting cut surface. It is common for a single Determine the color that consistently forms the outer layer of each microparticle. That way is ensures that a microparticle is read with a complete code. Is it the outer layer? an indicator segment, it is not read as part of the code.

The choice of core material for the onion ball depends in part on the material to be marked and its determination. In addition to the ability to further process the marked material survive, the core material should be sufficiently low Be large as well as easily divisible and be able to bond firmly with the surrounding pigmented To enter the shift.

Suitable core materials for most purposes are plastics such as polyolefins. Polyacrylates. Waxes, glass beads as well as biodegradable tvs Macromolecules such as albumin. Gunimiarabicuin, gelatin as well as polyvinylpyrrolidone. For a description of the manufacture of microbeads from different materials in the size range of preferably 50 to 200 μm diameter, which can be used as the core material suitable for the onion globules, reference is made to US Pat. No. 3,772,200 and 3,663,685.

The core of the microparticle can be a single thread made of, for example, nylon with such a small diameter be that it falls within the prescribed size range - preferably 25 to 200 μπι. Around the single core concentric colored layers are built up around it and the resulting microparticle can be Use as a means of subsequent identification even if it is several millimeters long. Alternatively the coated monofilament can be cut into pieces in order to achieve the one shown in FIG. 2 microparticles shown to train, which is referred to as "micro-disks" in the following. The micro-disk 26 has a monofilament core 28 and colored layers 30. which are so piled up concentrically on the core are that two consecutive layers are not the same color.

Those for the formation of the colored layers or segments of the onion globule or the micro-disc The dyes and pigments used are conventional and known to the person skilled in the art - for example inorganic pigments such as sulfates. Chromates. Sulphides. Oxides. Carbonates, etc., as well as stable organic ones Pigments such as phthalocyanine and Hansa yellow.

For example, a list of suitable colors might include:

Colorless clear Red blue black orange violet Brown yellow fluorescent Red White green fluorescent green

A comprehensive list of dyes and pigments can be found in the Color Index. 3rd edition, by F. M. Rowe (Ed.). published by the Society of Dyers and Colorists. Yorkshire, England.

The main requirements to be met by the colored layers are (1) the ability to form a firm bond to enter into with the core material and with each other so that the microparticle retains its physical wholeness, and (2) the lack of color or bleeding between the layers. The layers of paint are generally applied as a liquid resin system with the dye or pigment. An alternative Procedure is. successive layers of solvent-compatible and incompatible resins to apply. For example, one layer of a ketone-soluble resin, the next of an in Ketone insoluble resin are made up.

This succession of resin layers eliminates the need to apply each layer prior to application next to harden. Examples of resin systems in which dyes and pigments can be incorporated in order to achieve the Forming layers of color are, for example, the cellulose derivatives. Epoxy compounds. Polyolefins and waxes. The preferred materials are polyacrylics.

The concentric colored layers are applied to the core material using conventional methods - Including flowing or sparkling water. Ball mill. Dip processes or pharmaceutical tablet coating processes. A presently preferred method of coating spherical particles is

the use of a Wurster coating machine as described in US Pat. No. 3,241,520. The color resin can be dissolved or dispersed in a volatile solvent; is the pigment in one In the case of a low-viscosity liquid system, it may also be possible to apply it without a solvent.

The color-coded microparticle shown in Figure 3, What is to be referred to here as a "micro rosette" can be produced by using individual threads 34 of different sizes Color and preferably with a diameter of 5 to 50μιτι around a central core 38 in the form of a single thread in a regular arrangement into a heat-shrinkable one Wrap 36 of, for example, heat shrink plasticized polyvinyl chloride introduces.

Then heat is applied, causing the shell to contract to a smaller diameter. the colored single threads are kept in their regular arrangement during the drawing-in process and form a ring around the central core. Then you can turn the shell into microrosettes of the desired Cut length. If you take longer sections into a substance for the purpose of subsequent identification on, a cut along the cross-section may be required to remove the threads from around the core read the color-coded segments lying around. One of these single threads can be used as a starting point have a preselected color such as black or colorless-clear.

Materials that can be used to manufacture the microrosettes include: colored single threads made of polyamides, Polyesters, polyolefins, polyacrylics and modified celluloses. A preferred type of color coded Microparticle consists of microscopic particles of colored plastic film that are formed into a rectangular shape "Microsandwich" are fused together; see Fig. 4th

The microsandwich 40 is generally a rectangular hexahedron with 10 consecutive color segments 42. where two consecutive segments are not the same color. The code can be from the right to the left or vice versa. A key segment 44 with a predetermined color can also be used - for example black - built into the sequence to indicate the direction in which you can read the code got to.

Terminal segments are generally colorlessly clear or of a specific color to be easily identified to be able to determine whether a complete microsandwich or only part of one is present. The outer indicator segments are not read as part of the code.

The microsandwich identifiers decrease a double peel process as follows. Individual colored plastic sheets made of polyethylene or a other solvent-resistant plastics come in the special color sequence of the desired identification code stacked on top of each other. The thickness of each film is generally between 12 and 200 μm. The outside surface the bottom and top films of the stack are each coated with a release agent, which can be a resin material that fuses with the plastic film under the action of heat and is soluble in a solvent that does not attack the plastic film. Suitable release substances are for example polystyrene and polyvinyl alcohol. A commercial vinyl polymer is preferably used, that is a mixture of about 91% vinyl chloride, 3% vinyl acetate and 6% other ingredients and in methyl ethyl ketone is soluble (see Example 4 below).

Discs with a central hole are cut out of the stack of foils and placed on a mandrel stacked, with a large number of clear panes made of the solvent-resistant plastic over and under the color discs. This stack is heated (in the case of polyethylene film, for example, to 120 to 125 ° C for two hours), in order to fuse the film layers and form the material into a billet, which one then, as shown in FIG. 5 shows a tape 52 peeling.

The billet consists of clear plastic layers 48 which are fused with a color layer 50. the Color layer 50 normally consists of a multitude of code sequences separate from one another and from the clear ones Layers are separated by the release substance.

Release material is coated on both sides of the tape 52. You cut slices with a central hole from the coated tape and stacks them on a mandrel, as shown in FIG. 6 shows. This pile is heated in order to fuse the slices into a billet, which is then placed on the one shown in FIG. 5 shown Peeling way into a band with repetitive clear and colored surfaces. This tape brings is immersed in a solvent that will selectively dissolve the release material. This is how the individual microsandwiches are created.

The overall dimensions of the microsandwiches are determined by the thickness of the colored foils used and determines the thickness of the tapes that can be peeled off with the peeling device. The peeling technique becomes general in U.S. Patent Re 27,617.

Most materials do not require heating during peeling. In general is a Peel to a tape of 12.5 μίτι thickness sufficient. When using a plastic film of 65 μm thickness and Peeling into strips of 12.5 μm can therefore achieve a microsandwich whose individual segments Measure 64 χ 12.5 χ 12.5 μm. The total length of the sandwich depends of course on the number of segments present. Preferably each includes sandwich at least three segments representing the color code and an indicator segment at each end.

The choice of substances that make up the microparticles depends on the properties of the material, in which they are to be included. In certain cases the microparticles need to be specific to this material be matched to meet the special requirements of the material to be marked. That Survival of the microparticles after further processing and treatment of the material is the here • essential point of view

The invention is particularly well suited for marking bulk and bulk goods such as grains and Chemicals, animal and poultry feed and orally administrable pharmaceuticals for humans and animals. Liquid Products such as non-opaque paints and resins can be made with microparticles in low concentrations to mark.

Microsandwich identifiers are placed in dynamite and successfully recovered from the explosion debris after detonation. Farther paper and other solid products such as concrete have been successfully marked with microsandwiches

The color-coded microparticles should be homogeneously distributed in the material to be marked, and although preferably in an amount of 0.0001 to 1.0 part by weight per 100 parts by weight of the bulk material.

To facilitate homogeneous distribution, the microparticles should be tack-free at room temperature. Around to be able to know whether the bulk cargo has been subsequently diluted. is a careful adjustment of the Microparticle concentration required.

The recovery of the micro-identifiers from the manufactured product can be carried out in various ways The way to accomplish this depends on the type of microparticle used and the type of material being marked away. In the case of pulverulent bulk material, separation can generally be carried out visually. As a result Due to their peculiar shape and color, the microparticles can be easily distinguished when magnified. A fluorescent color in the code can be of special help here.

For some bulk goods, it is more convenient to separate the microparticles in a liquid because of their density properties. For example, polyethylene microsandwiches have been recovered from residues collected at the site of an explosion by placing them in a ZnCb solution of a specific gravity of \ 2 , in which the microsandwiches float and can thus be easily collected.

In order to facilitate the recovery of the microparticles, it is preferred in most cases magnetic iron oxide pigments or iron powder into the microparticles. The particles can then be easily Separate them magnetically from the surrounding material. This procedure is particularly useful for Separation of microparticles from explosion residues.

In the production of microsandwiches from extruded Polyethylene film encountered difficulties in extruding resin with high content of the magnetic Iron oxide (about 30% by weight). The extrusion problems can be overcome if you have iron powder (essentially spherical) are used in minor amounts (i.e. about 12 to 30%) in the polyethylene. The iron powder did not cover the foil color; the resulting micro-identifiers could be attached to a magnet recover easily.

When using a magnet to recover micro identifiers from bulk material, the The magnet is conveniently placed in an open plastic bag. The particles then adhere to the outside Bags that you simply turn inside out to hold the particles to hold on.

In the following examples, all quantitative data are parts by weight.

colored threads that are arranged in a regular order were arranged around a central core.

It is even better if the fused bundle is drawn to a diameter of less than 1000 μm 5 will.

Example 2

Beads made of microporous polymeric ion exchange resin (quaternary form of a polystyrene resin) with a diameter of about 500 to 750 µm used as a core for spherical color-coded microparticles ("onion globules").

Coating solutions were aminated by mixing 0.5 part of a polyamide resin with an amine from 290 to 300, with 5 parts of a bisphenol-A epoxy material made with an epoxy equivalent of 190. The polymer mixture was 5 parts Methyl ethyl ketone and two parts of chrome yellow pigment were added. A corresponding coating solution was made using red lead (97).

Two parts of the yellow colored resin-pigment mixture became 25 parts of the ion exchange resin beads put in a mixing vessel and mixed there until sticky.

Then two parts of the dry yellow pigment were added with continued rotating mixing, until the sticky surface of each bead was well coated with the dry pigment. The one with the yellow pigment coated beads were dried for half an hour at 88 ° C to gel the resin layer, and then sieve off the unused pigment from the coated parts.

The same procedure was repeated with the red and yellow resin-pigment mixtures until found four layers were on the pearls. The lot of color-coded pearls was passed through apertured sieves of 1000, 841 and 707 μπι sieved to remove pearl lumps and dry pigment residues.

Examination of a cut bead under the microscope revealed a sequence of four layers each about 5 μm thick.

Example 3 example 1

It became a bundle of polypropylene monofilaments in the colors red, green, yellow and blue with a diameter each of about 600 μπι in a preselected color sequence around a monofilament core in a sleeve of heat-shrink plasticized polyvinyl chloride tubing of about 30 cm in length and 3200 μπι diameter and a wall thickness of 400 μπι arranged.

The covered thread bundle held under tension was exposed to a blast of hot air during this the shell contracted to a diameter of about μπι. A merged one emerged Bundles of fibers in a matrix of polyvinyl chloride tubing. From the bundle were pieces of about μπι cut off length. Investigating this Microscopic rosettes under the microscope revealed individual identifiers in the form of microscopic disks produced by laying concentric layers on a nylon monofilament after the coating process

driving example 2 applied. The core thread with a diameter of 25 μπι was through a series sent through by resin-pigment coating solutions, The color sequence used is yellow, red, white and black (chrome yellow, red lead, titanium dioxide or Lamp soot) was.

Between each coating bath, the thread ran through a compressed air dryer at 100 ° C, in which the solvent escaped and the epoxy gelled enough to prevent the paint from bleeding.

After applying and drying the fourth layer of paint to a total diameter of about The coated single thread was 60 μπι through a Sent high-speed microtome to separate slices of a thickness of about 50 μπι.

If a relatively thick thread of about 25 μm diameter is used as the core, one can After applying the layers of paint, apply heat and tension to the diameter of the

9

|: to reduce layered monofilament. Coated

! äfj one single thread and pulls it on smaller ones

f1. Diameter should be the same Polymerisatmalcrial

|>; of the core can also be used for the coating,

| ϊ so that all parts of the coated single thread have the same

i; 5 have stretch properties. The single ones

;; Layers should be applied thinly and dry quickly.

jsj net to prevent mutual bleeding of the color

'; avoid layers. If you bring color layers from

j * 5 μm thick or less. can be a dark color

| v through an overlying light layer of paint-

|; v seem. However, since the code is of a cross-section

ti is read, represents the transparency of the thin

; Layers are not a problem.

I.

S example 4

§ This example explains the production of the micro

p sandwich particles after the double peeling process.

1 colored polyethylene sheets of a thickness of each

j, * 65 μηι were in the chosen color sequence, d. H. blue red.

|| stacked green, yellow and purple. The outer surface of the

f- Both outer foils of the stack were corona treated

4 and then with a release material of 10 weight

Ά share vinyl resin, 10 parts by weight ethyl alcohol and 30

; · Parts by weight of methyl ethyl ketone (MEK) coated

A Service.

'■, The stack of foils turned into discs with a

t diameter of about 15 cm and a central hole of

1 punched out about 6 cm and placed on a mandrel next to jo

Jj a plate stacked up to a height of 3.8 cm.

jl d. H. up to 40 repeating color codes. In the-

On the side of the colored discs, discs made of clear

tlyethylene arranged; after that the pile had a overall height of about 15 cm. j5

This stack was held at 120-125 ° C for two hours to fuse the layers together to form a plastic club.

This stick was then, as shown in FIG. 5 shows, peeled to an approximately 125 μm thick band. The vinyl release liner was applied to the top and bottom surfaces of the tape, then 15 cm discs were made Cut out of the ribbon with central holes 6 cm in diameter, towards a thorn stacked to a height of 15 cm and then held the stack at 120 to 125 "C for two hours to complete the layers to fuse and to form a plastic billet, as shown in FIG. 6 shows.

This stick became a band of 125 μm Thick peeled. The vinyl resin layer was removed by washing the tape in MEK, whereby the single. Microsandwiches were created, which are then air-dried became. · ·

The microsandwiches can be made magnetic, if iron powder in proportions of up to 30 is added to the resin mixture before the color foils are extruded Introduces wt .-%, the color of the film is not yet impaired. Each layer is given iron powder too, a concentration of about 12% by weight is sufficient. to easily recover the particles with the help of a magnet.

1 sheet of drawings

Claims (13)

Patent claims: 1. Microparticles. those for marking substances for the purpose of subsequent identification of the substances are suitable, characterized that each microparticle is an array of at least three visually distinguishable Has color segments, the sequence of which consists of a in a relevant to the labeled substance Information readable code consists, and that each microparticle is in its widest dimension over the color sequence 1 to 1000 μηι measures. 2. Microparticles according to claim 1, characterized in that that each of these microparticles contains up to 30% by weight of a magnetic substance. 3. Microparticles according to claim 1, characterized in that that each microparticle has a solid core with a coating thereon Has concentric layers of visually distinguishable colors, with no adjacent ones Layers of the same color are present. 4. microparticles according to claim 3, characterized in that that these colored layers are formed from pigmented polymeric material. 5. Microparticles according to claim 4, characterized in that that these layers of paint are made from pigmented mixtures of polyamide and epoxy resins are formed. 6. Microparticles according to claim 3, characterized in that this core consists of spherical particles with a diameter between 50 and 200 μm. 7. microparticles according to claim 3, characterized in that that this core is a single thread with a diameter of 25 to 200 μπι. 8. Microparticles according to claim 7, characterized in that this monofilament is a polyolefin monofilament is. 9. microparticles according to claim 1, characterized in that that the color segments of each microparticle in a ring around a central core are arranged around. 10. Microparticles according to claim 9, characterized in that each color segment is a colored one Single thread with a diameter of 5 to 50 μm is. 11. Microparticles according to claim 10, characterized in that that this single thread is fixed in a matrix made of polyvinyl chloride. 12. Microparticle according to claim 1, characterized in that the color segments of each microparticle be put by a series of layers that are parallel to a face of the microparticles get lost. 13. Microparticles according to claim 12, characterized in that that these color segments are formed from color films of an organic resin. 37 72 200 describes a marking method using refractory microparticles with small proportions of elements like manganese. Cobalt. Zinc. Cadmium and tin. The combinations of these elements with the Microparticles make up the various identification codes. These methods are particularly suitable for marking explosives such as dynamite. the Microparticles survive a detonation and can be detected in the explosive material. A similar marking process uses microparticles made from polymers such as polypropylene with small amounts of Elements are marked. These microparticles are preferably used for marking dynamite, since they don't make the nitroglycerin more sensitive. is The marking of substances using microparticles with identification codes serves the purpose of subsequent identification. As a result, individual product units of bulk materials are marked with microparticles which the user cannot easily discover and which do not interfere with the properties of the marked product. However, these methods have the disadvantage that the decoding is very complicated. If selected amounts of elements are incorporated in the microparticles, an electron microprobe analyzer is generally necessary for decoding, which is mostly in a remote location, which causes a delay between the detection of the microparticles and the reading of the code.
The known method for marking individual jo production units of a substance for the purpose of subsequent identification include the following Steps on: